Levels of serum inflammatory markers may be useful in identifying which athletes are more likely to require a longer recovery time after a sport-related concussion (SRC), new research shows.
Results of a prospective study examining inflammatory markers in high school and college football players shows two serum biomarkers, interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1RA), were notably elevated and significantly differentiated athletes with and without concussion.
In addition, post-concussion IL-6 levels were significantly associated with the duration of concussion symptoms.
"With so many people sustaining concussions and a sizeable number of them having prolonged symptoms and recovery, any tools we can develop to help determine who would be at greater risk of problems would be very beneficial, so these results are a crucial first step," principal investigator Timothy B. Meier, PhD, Medical College of Wisconsin in Milwaukee, said in a press release.
The study was published online July 3 in Neurology.
Two Candidate Biomarkers
Meier told Medscape Medical News that previous animal research and some clinical studies indicate there is an increase in particular inflammatory biomarkers within 24 hours of traumatic brain injury (TBI), and this led to the team's interest exploring this further.
"Very limited work has been done with a decently sized sample of athletes with concussion," he said.
The investigators' selection of specific inflammatory markers was based on previous studies of concussion. In addition to IL-6 and IL-1RA, these included IL 10, IL-1β, C-reactive protein (CRP), tumor necrosis factor (TNF) and interferon-γ (IFN-γ).
However, Meier noted there are numerous other inflammatory markers currently under investigation in traumatic brain injury.
A total of 857 high school and college football players were enrolled in the study. Of these, 41 concussed athletes and 43 matched control athletes who did not sustain a concussion during football season met the study's inclusion criteria.
All athletes underwent blood testing at the start of the football season. Those with concussions had blood tests within 6 hours after their concussion and again at 24 to 48 hours post-injury. Concussed athletes also had blood samples drawn 8, 15, and 45 days later. The control group had blood testing at similar times for comparison purposes.
Investigators found that of the seven biomarkers, two of them — IL-6 and IL-1RA — were both elevated 6 hours after concussion and significantly discriminated between study participants with and without concussion (IL-6 area under receiver operating characteristic curve [AUC], 0.79; 95% confidence interval [CI], 0.65 - 0.92; IL-1RA AUC, 0.79; 95% CI, 0.67 - 0.90).
